Hi Serpius,
So basically, adding a Noindex tag to a given page tells search engines (Google, Bing, etc) not to "index", or include that page in their search index. This means that when someone types in either keywords related to your site, or search for your site directly, those pages will
not show up in results.
So why would you want to do this?
There's a few reasons. Most site owners want to only show their most important pages in search results. For example, you don't want Google displaying a junk URL (which it happened to crawl and index) to someone who may potentially click through to either you or a competitor. You want your home, forum or categories being front and center.
Second, there's your Page Rank (PR) equity. Every website has only so much SEO "weight", or ranking, which can be distributed amongst their pages. Ideally, you want most of your PR to go into the important content - again such as your home or categories. The higher PR they have, the higher they will appear in search results - even to the sought after Page 1 of Google.
The more URLs you have at your site, the more
diluted the Page Rank becomes.
One problem is that CMS or forum platforms - whether phpBB, Wordpress, Xenforo, etc - add a vast amount of auxiliary pages which are unimportant from an SEO perspective. Anything you can click on at your site is potentially a URL which can be indexed in search results. These URLs may play a
useful or mechanical role in the operation of your website (i.e. the second-step page of a checkout process, or a confirmation page), but play no role in an SEO strategy.
For example, this is a real link produced by Xenforo Media Gallery which
can be indexed by Google:
https://www.nulumia.com/portfolio/g...ilm-strip-jump?direction=prev&jump_from_id=58
As you can see, it's definitely a "junk URL" from an SEO perspective and there's really no reason it should appear in search results. This is a scenario where you'd want to "Noindex" these pages, so Google or Bing will effectively ignore and omit them.
A thoughtful, proper Noindex strategy on a website can potentially clear thousands of URLs from your search index and redistribute their Page Rank
back to the pages that really count. During the relaunch of this website, roughly 4.5k URLs were removed, with a noticeable jump in Page Rank for the remaining pages not long after. I have also worked on client sites with as much as 15,000+ junk URLs successfully omitted.
One of the primary focuses of this addon is implementing comprehensive and fine-grained Noindex control, even into third-party Xenforo addons and the content they introduce.
Ask any questions you may have, and hope this clears things up!
-Robert